NV3550 with a 2nd gear grind. Why should I consider AX15 as a replacement?

What lube is in the NV3550? If you don't know it to be the right lubricant I'd drain it and refill it with Redline MTL and see what happens.

Jerry Bransford said:

What lube is in the NV3550? If you don't know it to be the right lubricant I'd drain it and refill it with Redline MTL and see what happens.

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I had the same problem. I followed Jerry's advice, and in a couple weeks, All Was Well. That was several years ago, and I haven't had a problem since.

Good/appropriate gear lubes aren't miracle workers, it sounds like you need some transmission work. And stop using Royal Purple, it's overpriced and it's only purple for marketing purposes... they add a purple dye to make it look different, that's all that is "special" about it.

Kaptainkid1 said:

I read all the time on this forum to replace instead of rebuild. It seems a new ax15 is about $2000 with tranny and replacement parts ie bell housing and shifter brackets.
A rebuild at a local tranny shop is $1600.
Is the rebuild really not worth it? They said I get a 2 year warranty and 30k.
What's everyone opinion?
Honestly I don't want to spend anymore money on my TJ. It's a 2002 4.0l with 170k. I'm considering another TJ with lower miles in the future.

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You don't need a bell housing for that swap, nv3550 and AX15 bells are the same. If the shifter bracket you're referring to is the one for the t-case shifter, I believe yours should be the one that goes under the t-case nuts and you can reuse that as well.

My 2000 TJ is at the tranny shop for a 3550 to AX15 swap. The 3550 died when a 3rd gear hard part broke (loud bang!). There is nothing but aftermarket parts for them since NVG closed. New transmission and rebuilt 231 (with slip yoke eliminator) from Novak. Note that the AX15 can use the same transmission mount as the 3550, but uses different threads in the housing - Novak AX15 threads are 7/16x14. The Novak shifter is a long straight stick, so I went with the B&M Sport Shifter, which is designed for the TJ and uses the same knob threads. Bought a new Crown knob and Mopar shift pattern insert. Drilled and tapped one corner of the B&M base 1/8x28 BSP for an ARB breather fitting, to be plumbed to the ARB breather already installed for the transfer case. The Savvy 231 cable shifter will swap over, as will the speedo gear. Have to extend the harness for the reverse lights from the driver side switch on the 3550 to the pax side on the AX15. Will fill the new AX15 with Red Line MT-90 (Red Line MTL greatly extended the life of my 3550).

After installation, we'll measure from the 231 yoke to the rear Dana 44 yoke, top and bottom, and send those measurements to Tom Wood's for a double cardan rear driveshaft. As they advised me, we will then use my adjustable Currie control arms to rotate the rear pumpkin up to make the pinion line up with the shaft.

Since this area will be opened, I also bought a LuK clutch, with National throw out bearing. The flywheel has 207K miles on it and we'll keep it if it looks good. As a backup, I got a LuK flywheel and new bolts - this LuK is advertised to have the correct domed engagement surface for the TJ. I threw in new lower and upper shift boots, too.

I don't follow the used market on AX15's. But I would search for a complete decent used setup for a bit since your Jeep is still functional. The AX15 is actually a breeze to rebuild if a person is mechanically inclined. Bearings and synchro's are easy to replace in one.

You could find a used one and run it as is. Or refresh and install. Just throwing that in here.

Is swapping to the 6 speed more work/cost? less desirable? Just noting that my 05' has the 6 speed. But second that I have the Redline oil work some wonders on transmissions synchro's but if your sure you put GL-4 product in the tranny (sounds like you did) and not the GL5 it does not seem like another oil change is going to help.

JustDandee said:

Is swapping to the 6 speed more work/cost? less desirable? Just noting that my 05' has the 6 speed. But second that I have the Redline oil work some wonders on transmissions synchro's but if your sure you put GL-4 product in the tranny (sounds like you did) and not the GL5 it does not seem like another oil change is going to help.

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The NSG370 is less desirable since it's known for having more problems and not as strong as the AX-15 or NV3550.

JustDandee said:

Is swapping to the 6 speed more work/cost? less desirable? Just noting that my 05' has the 6 speed. But second that I have the Redline oil work some wonders on transmissions synchro's but if your sure you put GL-4 product in the tranny (sounds like you did) and not the GL5 it does not seem like another oil change is going to help.

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it's a great transmission on paper and I loved the first gear, but they really commonly have issues with popping out of gear (mine was reverse) among other problems.

A swap would also be just about impossible because they also changed the crankshaft position sensor and put it in a different location at the same time they went to the nsg370. It's only possible to go the other way because a couple of companies have stepped in and produced AX15 bellhousings with NSG370 crank sensor locations. The NSG370 has an integral bellhousing so the transmission case would have to be made with the old sensor location.

My NV3550 is a little noisy going into second too, I’ve found that double clutching it helps substantially.
Reverse is the most problematic for me, reeeally wants to pop out.
Gonna put in some RP synchromax and hopefully that helps a bit. Would’ve gone with Redline MTL but can’t seem to find it around here.

James9100 said:

My NV3550 is a little noisy going into second too, I’ve found that double clutching it helps substantially.
Reverse is the most problematic for me, reeeally wants to pop out.
Gonna put in some RP synchromesh and hopefully that helps a bit. Would’ve gone with Redline MTL but can’t seem to find it around here.

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Don't waste your $$$ on Royal Purple even if it's a easy to find locally. https://www.amazon.com/dp/B000CPCBEG/?tag=wranglerorg-20

Jerry Bransford said:

Don't waste your $$$ on Royal Purple even if it's a easy to find locally. https://www.amazon.com/dp/B000CPCBEG/?tag=wranglerorg-20

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Already have it haha. I did check amazon before purchasing the RP, unfortunately up here in canada the Redline was $36 CAD for a quart bottle from amazon.ca. I got the RP cheaper than that. I couldn’t care less about the dye crap though.

The additional costs of some things are often well worth it.

I switched the 3550 to a Novak AX-15 and I've since purchased a used AX-15 for $350 with only 35K miles. Before buying new, I'd really look around for a good used AX-15. If you're done spending money on your Jeep then you'd need to do the transmission swap yourself. That's an involved job but not technically overwhelming. Might as well swap out the consumable clutch parts while it's out. You'd still need to find an appropriate shifter/stick shift.

I'm going to put my 2 cents in for RP Syncromax. In my research it and Redline were reccomended. Since it was available local I went with the Syncromax. I've never used RP before and have always passed it off as somewhat a gimmick.
Shifts were definitely improved, reverse is much easier to get into and pops out less and the take off rattle in 1st is lessened. Proofs in the pudding for me

Grant Lasson said:

I switched the 3550 to a Novak AX-15 and I've since purchased a used AX-15 for $350 with only 35K miles. Before buying new, I'd really look around for a good used AX-15. If you're done spending money on your Jeep then you'd need to do the transmission swap yourself. That's an involved job but not technically overwhelming. Might as well swap out the consumable clutch parts while it's out. You'd still need to find an appropriate shifter/stick shift.

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I’m curious, I’m looking at switching to a Novack AX-15. Why did you get a used AX-15? Did the other one crap out as well? And since you have gone both new and now used, in your opinion, if you had to do over, would you find a low mile used one versus the Novack one?

Jacone said:

I’m curious, I’m looking at switching to a Novack AX-15. Why did you get a used AX-15? Did the other one crap out as well? And since you have gone both new and now used, in your opinion, if you had to do over, would you find a low mile used one versus the Novack one?

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I would go with a good, used AX-15 if I had the choice. I bought the used one because of a bad case of angry sparrows that resulted in a cracked transfer case and several large gashes in my new AX-15 aluminum case. I swapped over the parts required from the used AX-15 to fix it. I have since tig welded the broken case so that I have a complete, working AX-15 on my garage floor should I ever need it.